Request for Review (s) - 7012980: PSOldGen is increased if there is no space in Metaspace

[Jon Masamitsu]

When full collections were being done because the Metaspace threshold was
reached, the Java heap was being expanded.  Changed the test for expanding
the Java heap to check that the GCCause was for a full old gen or for 
adaptive
size policy which is done in anticipation that a full GC will be needed 
before
the next young gen collection.

This change is done in two parts: the fix for this bug and a cleanup
to add the GCCause::is_system_gc().  This can be pushed separately
if desired.

http://cr.openjdk.java.net/~jmasa/7012980/webrev.fix.00/
http://cr.openjdk.java.net/~jmasa/7012980/webrev.is_system_gc.00/

https://bugs.openjdk.java.net/browse/JDK-7012980

Stability tested product and debug with gc_test_suite.  Performance tested
with specjbb2000 and specjbb2005 with and without MetaspaceSize set to
generate some Metaspace threshold caused full GC's.

Thanks.

Jon